Buck Rogers, Watch Out!

NASA researchers are studying insects and birds,
and using "smart" materials with uncanny properties
to develop new and mindboggling aircraft designs.

"Birds are so much more
maneuverable than our airplanes are today. Birds can hover, they
can fly backwards and sideways. And insects -- oh forget it!
-- upside down, loop-de-loop, all sorts of things." Anna McGowan,
program manager
for the Morphing Project at NASA's Langley Research Center

March 1, 2001 -- The "personal
aircraft" that replaces the beloved automobile in people's
garages may still lie in the realm of science fiction or Saturday-morning
cartoons, but researchers at NASA's Langley Research Center (LaRC)
are developing exotic technologies that could bring a personal
"air-car" closer to reality.

And air-cars are just the beginning.

Self-healing wings that flex and react like living organisms,
versatile bombers that double as agile jet fighters, and swarms
of tiny unmanned aircraft are just a few of the science-fiction-like
possibilities that these next-generation technologies could make
feasible in the decades ahead.

Above: Tomorrow's airplanes could
have self-bending wings, which might operate without flaps --thus
reducing drag and saving on fuel costs. Click on the image for
a 2 MB Quicktime movie
about some of the next-generation technologies being developed
at LaRC. Image courtesy of Robert
C. Byrd National Technology Transfer Center.

At the core of this impending quantum leap in aerospace technology
are "smart" materials -- substances with uncanny properties,
such as the ability to bend on command, "feel" pressure,
and transform from liquid to solid when placed in a magnetic
field.

"This is technology that most people aren't aware even
exists," said Anna McGowan, program manager for the Morphing
Project at LaRC, which develops these new technologies.

Left: Anna McGowan, program manager
for the Morphing Project at NASA's Langley Research Center.

The task of the Morphing Project is to envision what cutting-edge
aerospace design will be like 20 years from now and begin developing
the technologies to make it happen.

For example, a personal air-car needs to be compact, yet able
to fly at both very low and very high speeds.

"We know that to get a 'Jetsons' vehicle, you're probably
going to need a wing that can undergo a radical configuration
change," McGowan said. "The kind of wing you need at
very low speed and the kind of wing you need at high speeds are
completely different."

Some airplanes today can already reorient their wings, such
as the Navy's F-14 Tomcat and the B-1 supersonic bomber. These
planes use rigid wings mounted to large, heavy pivots in the
plane's body.

In contrast, Morphing Project scientists envision a wing that
will unfurl on command using "shape-memory" metal alloys
or other novel "smart" materials. The material of the
wing itself would bend to create the new shape.

Shape-memory alloys have the unusual property of snapping
back to their original shape with great force when a certain
amount of heat is applied. Any shape can be "trained"
into the alloy as its original shape.

Among the exotic "smart" materials being developed
by the Morphing Project, shape-memory alloys are relatively ordinary.

Imagine seeing a bullet shot through a sheet of material,
only to have the material instantly "heal" behind the
bullet! Remember, this is not science fiction. Self-healing materials
actually exist, and LaRC scientists are working to unravel their
secrets.

"What we did at NASA-Langley was basically dissect that
material to answer the question, 'how does it do that?'"
McGowan said. "By doing so, we can actually get down to
computational modeling of these materials at the molecular level."

"Once we understand the material's behavior at that level,
then we can create designer 'smart' materials," she added.

LaRC is also developing customized variations of piezoelectric
materials. These substances link electric voltage to motion.
If you contort a piezoelectric material a voltage is generated.
Conversely, if you apply a voltage, the material will contort.

Scientists can use such properties to design piezoelectric
materials that function as strain sensors or as "actuators"
-- devices that create small motions in machines, like the moving
of wing flaps.

Left: This thin, flexible film contains
a piezoelectric material that responds to the bend by producing
a voltage that's detected by the electrodes seen at the bottom
left of the image.

Combined with micro-electronics, these materials could lead
to a radical advance in airplane design.

"When we look 20 years into the future, we see airplanes
that have distributed self-assessment and repair in real time,"
McGowan said.

"To make this technology possible, you would need to
distribute these actuators and sensors throughout the wings.
That's similar to how the human body operates. We have muscles
and nerves all over our bodies -- so we are aware of what's happening
to our bodies and we can respond to it in a number of ways."

The resemblance to biology doesn't end there. One avenue of
Morphing Project research is to examine how nature does the things
that it does well. Scientists hope they can learn lessons from
this tutelage to improve their own designs.

"Nature does some things that we can't even get close
to doing. Birds are so much more maneuverable than our airplanes
are today. Birds can hover, they can fly backwards and sideways.
And insects -- oh forget it! -- upside down, loop-de-loop, all
sorts of things. We can't even get close to that [yet],"
McGowan said.

Called "biomimetics," this practice of learning
from nature has led to the development of -- among other things
-- a facsimile of bone.

Bone is very light because of its porous interior, but it's
also very strong. LaRC scientists can make structures similar
to bone by injecting polymer microspheres into composite shells
of the desired shape, then heating the spheres to make them fuse
together like tiny soap bubbles.

Right: LaRC scientists are studying nature to
understand how birds and insects achieve their high degree of
efficiency and maneuverability.

"If you can have the strength and lightweightness of
these bone-like structures that I'm talking about, then add in
nerve-like sensors and these flexible actuators, what you're
going to end up with is an extremely light-weight, very strong,
self-sensing, self-actuating structure."

Compare that vision to the rigid, numb, heavy structures airplanes
are made of today, and you'll get a sense of the dramatic difference
"smart" materials could make in aerospace design.

As with all basic science, the applications of these "smart"
materials will extend to technologies outside of the aerospace
industry.

"We are working very closely with two different commercialization
groups funded by NASA," McGowan said, "and the outlook
for this technology is on the order of millions of applications."

Web Links

NASA
Smart Materials and Structures -- technical information about
some of the next-generation technologies mentioned in this article,
including opportunities to express interest in technology transfer
opportunities. From the Robert C. Byrd National Technology Transfer
Center.

The Science and Technology Directorate at NASA's
Marshall Space Flight Center
sponsors the Science@NASA web sites. The mission of Science@NASA is to
help the public understand how exciting NASA research is and to help
NASA scientists fulfill their outreach responsibilities.